Auxin is essential for plant growth and development,also closely related to plant architecture.YUCCA(YUC)proteins catalyse the rate-limiting step for endogenous auxin biosynthesis.In this study,we identified 57 Bn YUC...Auxin is essential for plant growth and development,also closely related to plant architecture.YUCCA(YUC)proteins catalyse the rate-limiting step for endogenous auxin biosynthesis.In this study,we identified 57 Bn YUC genes in Brassica napus(rapeseed)genome,located on 17 chromosomes.Among them,A09 chromosome contained the most Bn YUCs as 6.Phylogenetic tree showed that all Bn YUC members were divided into 2 evolutionary clusters,including 7 sub-groups.Among the sub-groups,Clade I-C consisted 20 members,evolved independently from Arabidopsis thaliana,and motif 10 was unique.Genomic collinearity analysis showed that YUC collinear gene pairs widely existed in Brassica species,indicating that this family has a high retention rate in the evolution.Expression profile suggested that the Bn YUC family genes tended to express in specific growth/development stages as well as suffering stress/hormone treatments.It suggested that dominant expression of specific members existed with each development stage or treatment,indicating that each Bn YUC might have a clear division of work,and play a given biological function.This work was expected to build a basis for further study of the involvement of Bn YUC in growth,development and stress response.展开更多
Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. ...Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. Step one converts tryptophan to indole-3-pyruvic acid （IPA） by tryptophan aminotransferases followed by a rate-limiting step converting IPA to IAA catalyzed by YUCCA proteins. We identified eight putative StYUC （Solanum tuberosum YUCCA） genes whose deduced amino acid sequences share 50%-70% identity with those of Arabidopsis YUCCA proteins. All include canonical, conserved YUCCA sequences： FATGY motif, FMO signature sequence, and FAD-binding and NADP-binding sequences. In addition, five genes were found with -50% amino acid sequence identity to Arabidopsis trypto-phan aminotransferases. Transgenic potato （Solanum tuberosum cv. Jowon） constitutively overexpressing Arabidopsis AtYUC6 displayed high-auxin phenotypes such as narrow downward-curled leaves, increased height, erect stature, and longevity. Transgenic potato plants overexpressing AtYUC6 showed enhanced drought tolerance based on reduced water loss. The phenotype was correlated with reduced levels of reactive oxygen species in leaves. The results suggest a func-tional YUCCA pathway of auxin biosynthesis in potato that may be exploited to alter plant responses to the environment.展开更多
Somatic embryogenesis is an important experimental model for studying cellular and molecular mechanisms of early embryo development. Although it has long been known that removal of exogenous auxin from medium results ...Somatic embryogenesis is an important experimental model for studying cellular and molecular mechanisms of early embryo development. Although it has long been known that removal of exogenous auxin from medium results in somatic embryogenesis, the mechanisms underlying the initiation of somatic embryos （SEs） are poorly understood. In this study, we showed that YUCCAs （YUCs） encoding key enzymes in auxin biosynthesis are required for SE induction in Arabidopsis. To identify other factors mediating SE initiation, we performed transcriptional profiling and gene expres- sion analysis. The results showed that genes involved in ethylene biosynthesis and its responses were down-regulated during SE initiation. Ethylene level decreased progressively during SE initiation, whereas treatment with the metabolic precursor of ethylene, 1-aminocyclopropane-l-carboxylic acid （ACC）, or mutation of ETHYLENE-OVERPRODUCTION1 （ET01） disrupted SE induction, suggesting that ethylene plays a role in this process. Suppression of SE induction was also observed in the constitutive triple response 1 （ctrl） mutant, in which ethylene signaling was enhanced. These results indicate that down-regulation of not only ethylene biosynthesis, but also ethylene response is critical for SE induction. We further showed that ethylene disturbed SE initiation through inhibiting YUC expression that might be involved in local auxin biosynthesis and subsequent auxin distribution. Our results provide new information on the mechanisms of hormone-regulated SE initiation.展开更多
T-DNA insertion mutants have been widely used to define gene functions in Arabidopsis and in other plants. Here, we report an unexpected phenomenon of epigenetic suppression of T-DNA insertion mutants in Arabidopsis. ...T-DNA insertion mutants have been widely used to define gene functions in Arabidopsis and in other plants. Here, we report an unexpected phenomenon of epigenetic suppression of T-DNA insertion mutants in Arabidopsis. When the two T-DNA insertion mutants, yucl-1 and ag-TD, were crossed together, the defects in all of the ag-TD plants in the F2 popumation were partially suppressed regardless of the presence of yucl-1. Conversion of ag-TD to the suppressed ag- TD （named as ag-TD＊） did not follow the laws of Mendelian genetics. The ag-TD＊ could be stably transmitted for many generations without reverting to ag-TD, and ag-TD^＊ had the capacity to convert ag-TD to ag-TD^＊. We show that epige-netic suppression of T-DNA mutants is not a rare event, but certain structural features in the T-DNA mutants are needed in order for the suppression to take place. The suppressed T-DNA mutants we observed were all intronic T-DNA mutants and the T-DNA fragments in both the trigger T-DNA as well as in the suppressed T-DNA shared stretches of identical sequences. We demonstrate that the suppression of intronic T-DNA mutants is mediated by trans-interactions between two T-DNA insertions. This work shows that caution is needed when intronic T-DNA mutants are used.展开更多
基金the funding from the National Modern Agricultural Industrial Technology System(CARS-12)Tackling key problems in oil breeding in the 14th Five Year Plan of Sichuan Province(2021YFYZ0018)。
文摘Auxin is essential for plant growth and development,also closely related to plant architecture.YUCCA(YUC)proteins catalyse the rate-limiting step for endogenous auxin biosynthesis.In this study,we identified 57 Bn YUC genes in Brassica napus(rapeseed)genome,located on 17 chromosomes.Among them,A09 chromosome contained the most Bn YUCs as 6.Phylogenetic tree showed that all Bn YUC members were divided into 2 evolutionary clusters,including 7 sub-groups.Among the sub-groups,Clade I-C consisted 20 members,evolved independently from Arabidopsis thaliana,and motif 10 was unique.Genomic collinearity analysis showed that YUC collinear gene pairs widely existed in Brassica species,indicating that this family has a high retention rate in the evolution.Expression profile suggested that the Bn YUC family genes tended to express in specific growth/development stages as well as suffering stress/hormone treatments.It suggested that dominant expression of specific members existed with each development stage or treatment,indicating that each Bn YUC might have a clear division of work,and play a given biological function.This work was expected to build a basis for further study of the involvement of Bn YUC in growth,development and stress response.
文摘Indole-3-acetic acid （IAA）, a major plant auxin, is produced in both tryptophan-dependent and tryptophan-independent pathways. A major pathway in Arabidopsis thaliana generates IAA in two reactions from tryptophan. Step one converts tryptophan to indole-3-pyruvic acid （IPA） by tryptophan aminotransferases followed by a rate-limiting step converting IPA to IAA catalyzed by YUCCA proteins. We identified eight putative StYUC （Solanum tuberosum YUCCA） genes whose deduced amino acid sequences share 50%-70% identity with those of Arabidopsis YUCCA proteins. All include canonical, conserved YUCCA sequences： FATGY motif, FMO signature sequence, and FAD-binding and NADP-binding sequences. In addition, five genes were found with -50% amino acid sequence identity to Arabidopsis trypto-phan aminotransferases. Transgenic potato （Solanum tuberosum cv. Jowon） constitutively overexpressing Arabidopsis AtYUC6 displayed high-auxin phenotypes such as narrow downward-curled leaves, increased height, erect stature, and longevity. Transgenic potato plants overexpressing AtYUC6 showed enhanced drought tolerance based on reduced water loss. The phenotype was correlated with reduced levels of reactive oxygen species in leaves. The results suggest a func-tional YUCCA pathway of auxin biosynthesis in potato that may be exploited to alter plant responses to the environment.
文摘Somatic embryogenesis is an important experimental model for studying cellular and molecular mechanisms of early embryo development. Although it has long been known that removal of exogenous auxin from medium results in somatic embryogenesis, the mechanisms underlying the initiation of somatic embryos （SEs） are poorly understood. In this study, we showed that YUCCAs （YUCs） encoding key enzymes in auxin biosynthesis are required for SE induction in Arabidopsis. To identify other factors mediating SE initiation, we performed transcriptional profiling and gene expres- sion analysis. The results showed that genes involved in ethylene biosynthesis and its responses were down-regulated during SE initiation. Ethylene level decreased progressively during SE initiation, whereas treatment with the metabolic precursor of ethylene, 1-aminocyclopropane-l-carboxylic acid （ACC）, or mutation of ETHYLENE-OVERPRODUCTION1 （ET01） disrupted SE induction, suggesting that ethylene plays a role in this process. Suppression of SE induction was also observed in the constitutive triple response 1 （ctrl） mutant, in which ethylene signaling was enhanced. These results indicate that down-regulation of not only ethylene biosynthesis, but also ethylene response is critical for SE induction. We further showed that ethylene disturbed SE initiation through inhibiting YUC expression that might be involved in local auxin biosynthesis and subsequent auxin distribution. Our results provide new information on the mechanisms of hormone-regulated SE initiation.
文摘T-DNA insertion mutants have been widely used to define gene functions in Arabidopsis and in other plants. Here, we report an unexpected phenomenon of epigenetic suppression of T-DNA insertion mutants in Arabidopsis. When the two T-DNA insertion mutants, yucl-1 and ag-TD, were crossed together, the defects in all of the ag-TD plants in the F2 popumation were partially suppressed regardless of the presence of yucl-1. Conversion of ag-TD to the suppressed ag- TD （named as ag-TD＊） did not follow the laws of Mendelian genetics. The ag-TD＊ could be stably transmitted for many generations without reverting to ag-TD, and ag-TD^＊ had the capacity to convert ag-TD to ag-TD^＊. We show that epige-netic suppression of T-DNA mutants is not a rare event, but certain structural features in the T-DNA mutants are needed in order for the suppression to take place. The suppressed T-DNA mutants we observed were all intronic T-DNA mutants and the T-DNA fragments in both the trigger T-DNA as well as in the suppressed T-DNA shared stretches of identical sequences. We demonstrate that the suppression of intronic T-DNA mutants is mediated by trans-interactions between two T-DNA insertions. This work shows that caution is needed when intronic T-DNA mutants are used.
